On 5/15/07, Collin Anderson <[EMAIL PROTECTED]> wrote:
> class Laptop(models.Model):
> def laptops_out_on(date):
> 'get a list of laptops out on a given day'
> result = Laptop.objects.none()
> for x in Rental.objects.filter(checkout__lte=date,
> checkin__gte=date):
> result = result | x.laptops.all()
> return result
> laptops_out_on = staticmethod(laptops_out_on)
Why not get the list of active rentals (1 query) then get the list of
laptops associated with those rentals?
Also, make it a manager method rather than a static method.
class LaptopManager(models.Manager):
def checked_out(self, date=None):
if date is None:
import datetime
date = datetime.date.today()
active_rental_ids = [rental['id'] for rental in
Rental.objects.filter(checkout__gte=date,
checkin_lte=date).values('id')]
qs = super(LaptopManager, self).get_query_set().
return qs.filter(rental__id__in=active_rental_ids)
class Laptops(models.Model):
objects = LaptopManager()
#get all checked out laptops today:
Laptops.objects.checked_out()
...Code not tested since I can't sandbox a project and DB quickly just now.
More:
http://www.djangoproject.com/documentation/db-api/#lookups-that-span-relationships
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